In the oil and gas industry, particulate materials such as sand and other wellbore debris are often produced to the surface during the extraction of hydrocarbons from a well traversing unconsolidated or loosely consolidated subterranean formations. Producing such particulate matter can cause abrasive wear to components within the well, such as tubing, pumps, and valves, and can sometimes partially or fully clog the well creating the need for an expensive workover operation. Also, if the particulate matter is produced to the surface, it must be removed from the extracted hydrocarbons by various processing equipment at the surface.
In order to prevent the production of such particulate material to the surface, unconsolidated or loosely consolidated production intervals in the well are often gravel packed. In a typical gravel pack completion, a completion string including a packer, a circulation valve, a fluid loss control device and one or more sand control screens, is lowered into the wellbore to a position proximate the desired production interval. A service tool is then positioned within the completion string and a fluid slurry that includes a liquid carrier and a particulate material (i.e., gravel) is then pumped through the circulation valve and into the well annulus formed between the sand control screens and the perforated well casing or open hole production zone. The liquid carrier either flows into the adjacent formation or returns to the surface by flowing through the sand control screens, or both. In either case, the gravel is deposited around the sand control screens to form a gravel pack, which is highly permeable to the flow of hydrocarbon fluids but simultaneously blocks the flow of the particulate material often carried in the hydrocarbon fluids. As such, gravel packs can successfully prevent the problems associated with the production of particulate materials from the formation.
When pumping proppant through tools in high volumes, such as is required for fractured sand control applications (i.e., “frac pac”), proper positioning of a tool string relative to seal bores, ports, and valves is required to allow flow to divert in a proper direction. Undesirable flow diversion can lead to erosion of tools by flow of the proppant. In some instances, the tool string may become packed off, which can lead to lost or damaged tools or additional operations to attempt removal of the tools and proppant to recover the wellbore.
Traditionally, the location of tool strings is controlled by weight, by setting down against shoulders or smaller inner diameters with larger outer diameter tools, or by using devices such as collets to engage profiles to position tool strings. In deep and/or highly deviated wells, especially those where multiple zones are to be treated with a single work string, relying upon weight and pipe tally to know exactly where the tool string is positioned can be difficult. In such wells, pipe stretch and buckling prevent accurate position determinations.